Add 'docker' tag to docker-tests in task plugin

Change-Id: Idd05da21e5d351f98bc2e432a93de677bb3ef3d1
diff --git a/BUILD b/BUILD
index 06297ac..ec0e964 100644
--- a/BUILD
+++ b/BUILD
@@ -64,6 +64,7 @@
     args = ["--task-plugin-jar", "$(location :task)"],
     data = [plugin_name] + glob(["test/**"]) + glob(["src/main/resources/Documentation/*"]),
     local = True,
+    tags = ["docker"],
 )
 
 eslint(